In general, there is known, as an electrostatic coating apparatus, an electrostatic coating apparatus configured to comprise a coater operative to spray paint toward coating objects by using a rotary atomizing head, a high voltage generator operative to boost a power voltage to generate a high voltage to output the high voltage toward the rotary atomizing head of the coater, a power supply voltage control device operative to control a power supply voltage supplied to the high voltage generator, and a high-voltage control device operative to output, to the power supply voltage control device, a setting signal for setting a power supply voltage to control a high voltage outputted from the high voltage generator (Patent Document 1).
Since, for example, the rotary atomizing head constitutes an electrode for discharging a high voltage in such an electrostatic coating apparatus according to the conventional art, an electrostatic field is formed between the rotary atomizing head and a coating object caused to have an earth potential. Paint particles electrified so as to have a high voltage through the rotary atomizing head fly toward coating objects along electric lines of force of this electrostatic field so that they are deposited thereonto.